TO DOCTORS, a concussion – or more accurately, “traumatic brain injury” – is equivalent to a mini-death.

Six times in his short life, Eric Lindros has suffered that mini-death.

The most recent one has kept him off the ice for the past 15 months.

I will leave it to the puckheads to argue over whether or not Lindros is worth the price the Rangers are willing to pay to add him to their roster.

But it doesn’t take a hockey expert to know that trading away the future to sign a player whose career may last only as long as his next shift is not a calculated risk, but a plunge.

I don’t know much about hockey but I have had some first-hand knowledge of concussions.

From my experience, I can tell you this: They aren’t good. They stick around. And with very little provocation, they come back.

Lindros’ six concussions – that we know of – were not spread out over the course of 28 years, but over a period of 27 months. At one stretch of his career, he was averaging nearly a concussion a month, four in a five month period capped by the latest one, incurred when the Devils’ Scott Stevens leveled him in Game 7 of the 2000 Eastern Conference Finals.

That one was officially classified as a Grade II concussion, which includes brain dysfunction that lingers for more than 15 minutes after the incident. The worst is Grade III, which covers any period of unconsciousness, including as brief as a split second.

It is hard to believe that Lindros, who lay motionless on the ice for more than five minutes, did not lose consciousness and thus suffer a Grade III, or most severe variety of concussion.

In any event, there is no such thing as a minor concussion. A bruise on the brain is not the same as one on the shin. Neurosurgeons will tell you that the second concussion, no matter what the official classification, is far worse than than the first.

What about the sixth? Or the seventh?

Repeated concussions prematurely ended the careers of Troy Aikman and Steve Young and Pat LaFontaine and Al Toon and Lindros’ brother, Brett.

Who would be willing to gamble that, somehow, Eric Lindros will manage to escape the same fate?

Apparently, the Rangers, to the extent that they are willing to part with three of their brightest prospects, Jan Hlavac, Kim Johnsson and Pavel Brendl, and a draft pick, for a player who may lead them back to the Stanley Cup, or may not withstand his first solid hit.

This is not to say that Lindros shouldn’t continue to play hockey. He gets paid plenty of money to gamble with his own future.

And it is not to fire a warning shot over the heads of the Rangers, who are just as entitled to waste Chuck Dolan’s money as their basketball-bouncing breathren, the Knicks.

It is just to point out that the odds are against the Rangers reaping anything from this deal other than a few headlines and the right, however temporary, to boast of having added yet another marquee name to their all-time roster.

Could be Sather really believes Lindros will skate a charmed life this time around, or that the rest of the league will apply the Mario Rules to him and keep their mitts off.

None of them is a good reason to mortgage the future for a player so damaged that, if he were a fighter, would have trouble being licensed by the New York State Athletic Commission, hardly a bastion of caution or good judgment.

Because of his injury history, Lindros has barely averaged 50 games a season. He hasn’t played in more than a year. For a long time, considering his demands and the restrictive list of teams he would even consider joining, it looked as if he didn’t really want to play hockey anymore.

And who could blame him?

Playing hockey after having died six mini-deaths is dangerous.

Signing a hockey player with that kind of resume carries another label.